Conventionally, when an Internet Protocol (IP) stack is first initialized or when a new IP address is added, gratuitous Address Resolution Protocol (ARP) requests are sent out for the IP addresses of the local machine. ARP is a mechanism for finding a host's hardware address when only its network layer address is known. The number of ARP requests sent out is monitored by an ARP Retry Count parameter, which has a default setting of three, for example. If a machine replies to one or more ARP requests, then the IP address is already in use. When this happens, a Windows-based machine still boots, however the interface containing the offending IP address is disabled, a system log entry is generated, and an error message is displayed. If the machine that is defending the IP address is also a Windows-based machine, a system log entry is generated and an error message is displayed on that machine as well. However, the ARP caches of many machines in the network could be corrupt and when the machine is brought up using a non-offending IP address it has to re-send an ARP request. This restores the original values in the ARP cache of the other machine.
A machine using a duplicate IP address can be started when it is not attached to the network, in which case no conflict is detected. However, if it is then plugged into the network, the first time that it sends an ARP request for another IP address any Windows-based machine with a conflicting IP address detects the conflict. The machine detecting the conflict displays an error message and logs a detailed event in the system log. A sample event log entry is: the system detected an IP address conflict for IP address 199.199.40.123 with the system having network hardware address 00:DD:01:OF:7A:B5. Network operations on this system are disrupted as a result. Dynamic Host Configuration Protocol (DHCP)-enabled clients inform the DHCP server when an IP address conflict is detected and, instead of invalidating the IP stack, request a new IP address from the DHCP server. They also request that the DHCP server flag the conflicting IP address as corrupt.
For an Open Shortest Path First (OSPF) network, link state advertisements are used to determine if there are duplicate router identifications (IDs). A duplicate router ID can be detected and propagated to other routers in the OSPF area. However, a user must manually go to every router in the network and use a series of commands to show the router ID and determine the address.
OSRP is an optical routing protocol similar to PNNI (Private Network-to-Network Interface) and MPLS (Multiprotocol Label Switching), which was developed for Asynchronous Transfer Mode (ATM) networks. Through OSRP, switches can exchange information about the network and the status of switches and links. OSRP works in an environment of switches that handles multiple wavelengths of light as circuits, automatically provisioning entire wavelengths or fractions of wavelengths available on a fast-switched basis.
Open Systems Interconnection/Intermediate System-Intermediate System (OSI/IS-IS) is an OSI link-state hierarchical routing protocol that floods a network with link-state information to build a picture of network topology. OSI/IS-IS operates by sending “hello” packets to all OSI/IS-IS enable interfaces to discover neighbors and establish topology.
Conventionally, OSRP and OSI/IS-IS-based networks do not include mechanisms to quickly and efficiently determine which router or machine is causing a network problem. Thus, the user Man take days to determine the identify of the router, machine, or switch in question in response to network problems, such as misconfiguration.